Products > Test Equipment
Test Equipment Anonymous (TEA) group therapy thread
mnementh:
--- Quote from: tautech on June 01, 2018, 11:25:37 pm ---
--- Quote from: mnementh on June 01, 2018, 10:47:37 pm ---Aaaand now we've just gone recursive... :palm:
...right back to my original statement that the "the "one or the other" argument is just plain stupid. Each excels at different things, and decent CROs are cheap and plentiful enough that there's simply no good reason NOT to have both on your bench.
--- End quote ---
It's not stupid !
You conveniently overlook the fact many don't have the skill, tools or understanding to maintain or repair a CRO and yes a 2465 or any from the same family are excellent scopes but the complexity that is encountered in attempting repair of one is way past what many would choose to undertake. Some might say that their current market value is no more than $1/MHz for good reason.
When looking at the bigger picture for those wanting their first scope none of the above can or should be discounted.
--- End quote ---
Dude... you need a Tin Woodsman, a Cowardly Lion and an impertinent Teenage Girl in red slippers to go with that Straw Man you've got there. ::)
For THOSE folks, do you REALLY think a DSO, with basic features often buried under multiple levels of menus and all of the complexities of digital sampling theory to learn in order to use properly, is a better choice when you're already trying to learn "This is an Amp, this is a Volt, together with Resistance, Inductance and Capacitance they make everything electronic go" fundamentals? Especially in a time when you can pick up a working CRO for $50-150 (often with warranty) on fleaBay ANY DAY of the week?
Arguing that you HAVE TO CHOOSE ONE OR THE OTHER is stupid; therefore any argument predicated upon that notion is similarly stupid.
mnem
|O ::) |O :o |O
tautech:
--- Quote from: Specmaster on June 01, 2018, 09:50:37 pm ---I also tend to think (as a none user/owner of a DSO other that a lowly DSO138) that the screen is a bit off putting as the traditional CRO is a 8 x 10 grid and the DSO is a 8 x 15 grid and I suspect thats could be a trap for a new player as I suspect that they would try to replicate the imagery shown on a CRO on DSO which is never going to look the same as the display is going to look stretched width-ways. Also the image on the 2465 is considerably cleaner looking than the DSO and TBH I would have expected the DSO to have been the cleaner image seeing as it set to a higher v/div, lifting it further away from any background noise factor :-//
--- End quote ---
Some deeper understanding of the basic differences and operation principles between a CRO and DSO are needed.
Analog CRO's are just that, analog, in the way that there's a defined signal path all the way to the CRT but let's just look at the vertical axis for simplicity.
What produces the clean crisp trace is the quality of the CRT and associated circuitry, after all it's just only a stream of electrons that needs to be only wide enough to provide good resolution/visibility.
DSO's on the other hand as tggzzz briefly comments on, gather data sample points and then plots them on the display by way of reconstruction and then interpolation to display the waveform we recognize.
Unlike a CRO where the display is near realtime, the DSO display cannot be updated at such high rates as a CRO sweep so the imagery is uploaded as a 'batch' if you like to the display at much slower rates.
So within each batch even for a repetitive waveform there are variations in the data points that manifest themselves in an apparently fussy displayed trace. Lower display vertical pixel counts can suppress this to some degree but we want higher vertical resolution not lower.
So how do we clean up the traces to something like a CRO ?
There's a couple of common solutions, HiRes/ERES or Averaging.
They achieve similar results but HiRes preserves waveform detail better.
Simply if we think of the 3 lines of data below then extract the upper and lower for a more defined trace.
---------------------------------------------------------------------------------------
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Dave's done a couple of vids to help DSO owners get their heads around how to deal with their apparently noisy scopes:
https://www.eevblog.com/2014/04/10/eevblog-601-why-digital-oscilloscopes-appear-noisy/
https://www.eevblog.com/2014/04/27/eevblog-610-why-digital-scopes-appear-noisy-part-2/
Mr. Scram:
--- Quote from: mnementh on June 02, 2018, 01:21:41 am ---Dude... you need a Tin Woodsman, a Cowardly Lion and an impertinent Teenage Girl in red slippers to go with that Straw Man you've got there. ::)
For THOSE folks, do you REALLY think a DSO, with basic features often buried under multiple levels of menus and all of the complexities of digital sampling theory to learn in order to use properly, is a better choice when you're already trying to learn "This is an Amp, this is a Volt, together with Resistance, Inductance and Capacitance they make everything electronic go" fundamentals? Especially in a time when you can pick up a working CRO for $50-150 (often with warranty) on fleaBay ANY DAY of the week?
Arguing that you HAVE TO CHOOSE ONE OR THE OTHER is stupid; therefore any argument predicated upon that notion is similarly stupid.
mnem
|O ::) |O :o |O
--- End quote ---
That brings us back to my previous question. Where are the modern Keysight or R&S CROs? If CROs provide something that DSOs cannot, why aren't we seeing any serious contender producing them for that use? There are a plethora of niche use instruments that are sold for eye watering amounts of money because they do that one thing that nothing else can do, but CROs do not seem to be in that group.
Brumby:
If I were to introduce someone to the world of oscilloscopes, I would start off with my Hitachi 2 channel 15MHz CRO.
Doesn't mean I will dissuade them from getting a DSO.
Now - please - let's walk away from this pointless haranguing ... or I'll start posting pics of my DSO138!
bd139:
--- Quote from: Mr. Scram on June 02, 2018, 03:16:09 am ---
--- Quote from: mnementh on June 02, 2018, 01:21:41 am ---Dude... you need a Tin Woodsman, a Cowardly Lion and an impertinent Teenage Girl in red slippers to go with that Straw Man you've got there. ::)
For THOSE folks, do you REALLY think a DSO, with basic features often buried under multiple levels of menus and all of the complexities of digital sampling theory to learn in order to use properly, is a better choice when you're already trying to learn "This is an Amp, this is a Volt, together with Resistance, Inductance and Capacitance they make everything electronic go" fundamentals? Especially in a time when you can pick up a working CRO for $50-150 (often with warranty) on fleaBay ANY DAY of the week?
Arguing that you HAVE TO CHOOSE ONE OR THE OTHER is stupid; therefore any argument predicated upon that notion is similarly stupid.
mnem
|O ::) |O :o |O
--- End quote ---
That brings us back to my previous question. Where are the modern Keysight or R&S CROs? If CROs provide something that DSOs cannot, why aren't we seeing any serious contender producing them for that use? There are a plethora of niche use instruments that are sold for eye watering amounts of money because they do that one thing that nothing else can do, but CROs do not seem to be in that group.
--- End quote ---
No one wants them. As I said earlier, if I was running a business I’d use a DSO.
Also a point: when you have no scopes to start with, and that may be because you have an empty bench to fill at your company or university or home, then you tend to have to make the transition to having a scope. At that point the cost benefit of a DSO is much better.
At the bottom end, a DS1054Z is perfectly fine for most noddy industrial and personal users. Even going back to my short spell in industry, we had an inferior 100MHz DSO on bench. The nice scopes were pooled. Nice scopes being some 7000’s which were indication only and some high end HP.
CROs in 2018 are 100% dead. Apart from those of us who still like them. And that’s fine.
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